Studies on the tosylation of cellulose in mixtures of ionic liquids and a co-solvent

• Published in: Carbohydrate polymers 2012-06, Vol.89 (2), p.526-536
• Main Authors: Gericke, Martin, Schaller, Jens, Liebert, Tim, Fardim, Pedro, Meister, Frank, Heinze, Thomas
• Format: Article
• Language: English
• Subjects: Acetamides - chemistry; Allyl Compounds - chemistry; Applied sciences; cellulose; Cellulose - chemistry; Cellulose and derivatives; Cellulose derivatization; Chromatography, Gel; Co-solvents; cooling; Dimethyl Sulfoxide - chemistry; Ethylamines - chemistry; Exact sciences and technology; Fourier transform infrared spectroscopy; gel chromatography; Homogeneous synthesis; Imidazoles - chemistry; Ionic liquids; Ionic Liquids - chemistry; Lithium Chloride - chemistry; Magnetic Resonance Spectroscopy; molecular weight; Natural polymers; nuclear magnetic resonance spectroscopy; Organophosphates - chemistry; Physicochemistry of polymers; polymers; Pyridines - chemistry; Solvents - chemistry; Spectroscopy, Fourier Transform Infrared; Tosyl cellulose; Tosyl Compounds - chemistry; viscosity
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2012.03.040

► Tosyl celluloses can be prepared by homogeneous derivatization in mixtures of ionic liquids and a co-solvent. ► Reaction time, molar ratio, and type of base determine the properties of the products obtained. ► NMR- and FT-IR spectroscopy as well as SEC were used to characterize tosyl celluloses with DStosyl≤1.14 and DSCl≤0.16. ► Tosyl- and chloro-deoxy groups could be substituted completely by azide. ► Recycling of ionic liquids and co-solvents could is possible. The tosylation of cellulose in ionic liquids (ILs) was studied. Due to the beneficial effect of different co-solvents, the reaction could be performed at 25°C without the need of heating (in order to reduce viscosity) or cooling (in order to prevent side reactions). The effects of reaction parameters, such as time, molar ratio, and type of base, on the degree of substitution (DS) with tosyl- and chloro-deoxy groups as well as on the molecular weight were evaluated. Products with a DStosyl≤1.14 and DSCl≤0.16 were obtained and characterized by means of NMR- and FT-IR spectroscopy in order to evaluate their purity and distribution of functional groups within the modified anhydroglucose unit (AGU). Tosylation of cellulose in mixtures of IL and a co-solvent was found to result in predominant substitution at the primary hydroxyl group. Size exclusion chromatography (SEC) revealed only a moderate degradation of the polymer backbone at a reaction time of 4–8h. Finally, the nucleophilic displacement (SN) of tosyl- and chloro-deoxy groups by azide as well as recycling of the ILs was studied.